Filter with exterior and interior media components and method of filtering

ABSTRACT

The invention features a filtration segment having a top seal, a bottom seal and a primary filter core and the method of filtering with the design of the filtration segment. The primary filter core is operatively coupled to at least one opening which is located either on the top seal or on the bottom seal. The filtration segment also includes one or more interior filters surrounding the primary filter core. Each interior filter includes a filter material surrounding a secondary core which is operatively coupled to at least one opening which is located either on the top seal or on the bottom seal. Each filter may optionally include a retaining medium enclosing the filter material. The filtration segment has one or more layers of an exterior filter media which operatively surround the interior filters and are operatively coupled to the top seal and the bottom seal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 60/989,338 filed on Nov. 20, 2007, incorporated in its entirety by reference.

BACKGROUND

This invention generally relates to the field of fluid filtration.

Filters and methods of filtration are widely utilized in a number of commercial and industrial applications and also in laboratory, clinical and residential settings. Such filters and methods may be used to purify fluids (e.g., liquids and gases) and to extract compounds (e.g., fluids and solids) contained in the fluids.

The present invention presents a unique design and method for fluid filtration.

SUMMARY OF THE INVENTION

In general, the invention features a filtration segment having a top seal, a bottom seal and a primary filter core. The primary filter core is operatively coupled to at least one opening which is located either on the top seal or on the bottom seal. The filtration segment also includes one or more interior filters surrounding the primary filter core. Each interior filter includes a filter material surrounding a secondary core which is operatively coupled to at least one opening which is located either on the top seal or on the bottom seal. Each filter may also include a retaining medium of a rigid or semi-rigid support surrounding the inside, outside or both sides of the filter material. The filtration segment has one or more layers of an exterior filter media surrounding the interior filters and are operatively coupled between the top seal and the bottom seal. The exterior filter media may be supported by a rigid or semi-rigid material to maintain its integrity. The method generally involves flowing a fluid around the exterior filter media while at the same time flowing the remaining fluid through the cores of the interior filters. The seals prevent the fluid from passing into the primary filter core which can be cylindrical fluid permeable material or a void formed by the space outside the interior filters and inside the exterior filter media.

The method can also include the reverse flow. The unfiltered fluid passed from the interior of the outer filter media to the exterior while at the same time part of the fluid to be filters passes from the interior to the exterior of the interior filters. The filtered fluid collects outside the flirtation segments which can be in a housing.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of an embodiment of a filtration segment showing the top seal.

FIG. 1B is a side view of the filtration segment of FIG. 1A.

FIG. 2A is a cross-sectional view of an embodiment of the filtration segment of FIG. 1B.

FIG. 2B is a cross-sectional side view of the filtration segment of FIG. 1A in an embodiment of use showing an outside-in flow path.

FIG. 2C is a cross-sectional top view of the filtration segment of FIG. 2B showing an outside-in flow path.

FIG. 2D is a cross-sectional side view with no openings in the top seal.

FIG. 3 is a cross-sectional top view of an alternate embodiment of the filtration segment of FIG. 1A with different size interior filters.

FIG. 4 is a cross-sectional top view of another alternate embodiment of the filtration segment of FIG. 1A with granular material.

FIG. 5A is a cross-sectional side view of the filtration segment in an alternate embodiment of use showing an inside-out flow path.

FIG. 5B is a cross-sectional top view of the filtration segment of FIG. 5A showing an inside-out flow path.

FIG. 6 is a cross-sectional side view of the filtration segment in a double stack arrangement with an outside-in flow path.

FIG. 7 is a cross-sectional side view of the filtration segment in a double stack arrangement with an inside-out flow path.

FIG. 8A is a cross-sectional side view of the filtration segment in a cross-flow configuration.

FIG. 8B is a cross-sectional side view of the filtration segment in a cross-flow configuration with a double stack arrangement.

FIG. 8C is a schematic drawing showing the flow pattern of a filtration system in a cross-flow configuration.

FIG. 9 is a cross-sectional side view of the filtration system in an alternate embodiment of a cross-flow configuration.

FIG. 10 is a cross-sectional side view of the filtration system in an alternate embodiment where the top seal is completely closed.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1A and 1B depict one embodiment of the present invention. FIG. 1A is a top perspective view of a filtration segment 10 sealed at opposite-ends by a top seal member 12 and a bottom seal member 14. FIG. 1B is a side view of the filtration segment 10 as shown in FIG. 1A. In this embodiment, the top seal member 12 includes a primary opening 22 a, which generally occupies the center portion of the top seal member 12, as well as one or more secondary openings 32 a, which are generally arranged in a circular pattern surrounding the primary opening 22 a. To facilitate the sealing of the primary opening 22 a by a top cap 40 (not shown in FIGS. 1A and 1B, but shown in FIG. 2B), or to facilitate the stacking of multiple filtration segments 10 on top of one another (which will be discussed in more detail in FIGS. 6 and 7 below), in a preferred embodiment, a ring-shaped flange 23 a is provided around the primary opening 22 a. Preferably, the flange 23 extends both upwardly from the surface of the top seal member 12 and downwardly into the body of the filtration segment 10, so as to form a sealing/coupling surface 27 for receiving a top cap 40 or a stacking adaptor 70 as will be discussed in more detail below.

Similarly, in this embodiment, the bottom seal member 14 has a primary opening 22 b (as shown in FIG. 1B, one or more secondary openings 32 b (not shown in FIGS. 1A and 1B, but shown in FIG. 2B), as well as a ring-shaped flange 23 b. The positions of the primary opening 22 b and the secondary opening 32 b in the bottom seal member 14 generally correspond to the positions of the primary opening 22 a and the secondary opening 32 a in the top seal member 12.

The top seal member 12 and the bottom seal member 14 are preferably made of materials that are impermeable to the fluids that are to be filtered. The top seal member 12 and the bottom seal member 14 each may have a lip 34 extending over the edge of the exterior filter 16. The lips 34 help maintain the shape of exterior filter 16 of the filtration segment 10.

FIGS. 2A-2C depict the cross-sectional views of a filtration segment 10 according to one embodiment of the current invention. In particular, FIG. 2A is a cross-sectional top view of the filtration segment 10. FIG. 2B is a cross-sectional side view of the filtration segment 10 of FIG. 1. FIG. 2C is another cross-sectional top view of the filtration segment 10. FIGS. 2B and 2C show one use of the present invention wherein liquids are filtered and then collected at the center portion of the filtration segment 10. Another use of the present invention wherein liquids are filtered and then collected at the peripheral portion of the filtration segment 10 is depicted in FIGS. 5A and 5B below.

Referring to FIG. 2A, in one embodiment -of the current invention, the filtration segment 10 includes an exterior filter 16 and one or more interior filters 18 (18 a, 18 b, 18 c, etc.). The exterior filter 16 encloses the interior filters 18. The total number of the interior filters 18 equals to the total number of the secondary openings 32, and the positions of the interior filters 18 correspond substantially to those of the secondary openings 32 a and 32 b located on the top seal member 12 and bottom seal member 14, respectively. Therefore, when the filtration segment 10 is properly assembled, the top seal member 12 covers the upper ends of the exterior filter 16 and the interior filters 18, the bottom seal member 14 covers the lower ends of the exterior filter 16 and the interior filters 18, and the interior filters 18 are in fluid communication with the secondary openings 32 a and 32 b. Although the cross-sectional shapes of the exterior filter 16 and interior filters 18 are shown as being circular, any cross-sectional shape may be used.

In some embodiments, each of the filters (i.e. exterior filter 16 and the interior filters 18) comprises a filter media situated between two concentrically arranged cages. Accordingly, with respect to the exterior filter 16, the filter media is positioned between an outer cage 19 o and an inner cage 19 i; with respect to each of the interior filters 18, the filter media is positioned between an outer cage 29 o and an inner cage 29 i. The cages help to maintain the structural integrity of the filters. The cage may also be beneficial when the filtration system is in the reverse flow pattern as discussed in FIGS. 5A and 5B below.

However, it is not always necessary to use two cages to house the filter media. Depending on the material and structure of the filter media, and factors such as the pressure to be used in the filtration system, more or less cages can be used in the current invention. For example, in some embodiments, only one cage is needed for each filter, and such single cage can be either an outer cage (such as 19 o or 29 o) or an inner cage (such as 19 i or 29 i). In some other embodiments, no cage is needed at all. One example is when pleated metal is used as the filter media in the filtration segment. Because pleated metal is capable of maintaining its physical structure under most circumstances, it is often not necessary to use cages to retain the media.

People skilled in the art can readily perceive that filters with none, one or more cages can be mix-matched in a single filtration segment, depending on the particular demands of each filtration process. For example, in one embodiment, an outer cage is provided for the exterior filter 16, but no cage is provided for the interior filters 18. All such variations are within the scope of the current invention.

The cages shown are illustrative of the use of a rigid or semi-rigid support such a synthetic netting support that allows fluid flow through the media. Any type of material that supports the filter media and allows fluid flow may be used.

The cages 19 or 29 can be in various forms. In some embodiments, the cages are shaped as springs or concentric rings. In some other embodiments, the cages are in the form of fluid permeable sleeves that support the filter media, polymer meshes, or cinch straps. In a preferred embodiment where pleated metal is used as the filter media, the housing cage is in the form of a metal spring. In a preferred embodiment when pleated non-metal is used, the preferred cage is a synthetic mesh.

Various forms of filter media can be used in the current invention. Examples include, but are not limited to, pleated media, spun media, granular media, solid media and other media known to those skilled in the art. Similarly, various types of materials can be used in the current invention, including, but not limited to, metal, fiberglass, cellulose, synthetic media such as polypropylenes, or polyethylene, polyester, cloth, paper, nylon, orlon, teflon and combinations thereof. In one preferred embodiment, the filter media is made of pleated synthetic media. The filter segment may be single use and disposable or reusable.

FIG. 2B shows a longitudinal cross-sectional view of the filtration segment 10 secured in a housing 36 according to one embodiment of the invention. The filtration segment 10 may be secured in the housing 36 by an assembly including a rod 38, a top cap 40, a bottom cap 42, a nut 44, and a post 49. The rod 38 is inserted through the primary opening 22 a, an opening in the top cap 40, the primary opening 22 b and an opening in the bottom cap 42. The rod 38 can be secured by a nut 44 or any other means known in the art. Fluids may enter the housing 36 via an inlet 46 and exit via an outlet 48. The fluids may be pressurized or may flow by gravity. Preferably, the fluid is under pressure so that it flows more smoothly and efficiently.

The top cap 40 seals the primary opening 22 a. In one embodiment, the seal is achieved by engaging the top cap 40 in close contact with the ring-shaped flange 23 a (not shown) and/or the sealing surface 27 (not shown) as depicted in FIG. 1A above. Consequently, fluids entered from the inlet 46 of the housing 36 will not be able to access the inside of the filtration segment 10 via the primary opening 22 a. Similarly, at the bottom of the filtration segment 10, the post 49 also forms a seal around the primary opening 22 b, so that unfiltered fluids entered from the inlet 46 of the housing 36 may not flow along the peripherals of the filtration segment to the bottom of the filtration segment 10 to access the inside of the filtration segment 10 via the primary opening 22 b.

As shown in FIG. 2A and 2B, there can be multiple interior filters 18 a, 18 b, 18 c, 18 d and 18 e which, according to some embodiments of the invention, are spaced in such a manner that they collectively surround an area that is generally along the central axis of the exterior filter 16. This area is referred to as the primary filter core 20, which extends from the primary opening 22 a in the top seal member 12 to the primary opening 22 b in the bottom seal member 14. The exterior filter 16 can be secured to the top seal 12 and bottom seal 14 by o-rings (not shown) disposed between the edges of seals surrounding the top and bottom portion of the filter 16. This modification facilitates construction of the filter segment. In a preferred embodiment, the primary filter core 20 is simply a void. Alternatively, the primary filter core 20 is a cylindrical tube with perforations or a cylindrical tube made of a fluid permeable material. In the embodiment as shown in FIG. 2B, the primary filter core 20 is a void. The upper end of the opening to the primary filter core 20 is sealed by the top cap 40 and the lower end of the primary filter core 20 is in fluid communication with the outlet 48 via perforations in the bottom cap 42.

Similarly, a secondary filter cores 28 a-e can be formed along the central axis in each of the interior filters 18. The upper end of the secondary filter core 28 is in communication with an opening 32 a in the top seal member 12. The lower end of the secondary filter core 28 is in communication with an opening 32 b in the bottom seal member 14.

As shown by the arrows in FIGS. 2B and 2C, in a preferred embodiment, the unfiltered fluid enters the filter assembly via the inlet 46. The fluid then flows through one of the following two filtration routes:

-   -   The fluid first enters the secondary filter cores 28 of the         interior filters 18 via the openings as shown at 32 a in top         seal 12, passes through the filter media of interior filters 18         from the inside of the filter to the outside of the filter, then         enters into the various voids 50 in the filtration segment 10,         and is eventually collected in the primary filter core 20 in         communication with the voids 50.     -   The fluid first flows along the inner walls of the housing 36 to         the peripheral area surrounding the exterior filter 16, then         passes through the exterior filter 16 from the outside of the         filter to the inside of the filter, enters into the various         voids 50 in the filtration segment 10, and is eventually         collected in the primary filter core 20.

FIG. 2D is a variation of the filter segment 36 where top seal 80 has no openings for fluid flow into interior filters 18. The fluid flow enters the interior filters only from the opening in the bottom seal 14. Otherwise the filtration is the same as shown in 2B and 2C.

There may be one or more voids 50 in the filtration segment 10. The number and shape of voids 50 depend upon the shape, size and arrangement of the interior filters 18. The voids 50 are in communication with primary filter core 22. All filtered fluids collected in the primary filter core 20 then pass through the bottom cap 42 and exit the filter assembly via the outlet 48.

FIG. 3 illustrates an alternate embodiment of the filtration segment 10 having the interior filters 18 with two different diameters. Interior filters 18 u, 18 v and 18 w are smaller than interior filters 18 x, 18 y and 18 z. In some embodiments, all the interior filters 18 may be of different diameters, shapes or sizes. Also shown in FIG. 3 is an embodiment where no cage is provided for the interior and exterior filters.

FIG. 4 illustrates an embodiment of the filtration segment 10 with various sizes of interior filters 18. Also shown is an embodiment where a filter media 52 is used to fill the voids 50 of the filtration segment 10. The filter media 52 may be granular, such as carbon. Alternatively, it can be any other filter media or combination thereof. The filter media generally fills and is distributed in the void 50 defined by the exterior filter 16 and the interior filters 18. If the filter media 52 is a granular media, the primary filter core 20 is preferably a cylindrical tube with fine perforations or a cylindrical tube made of a fluid permeable material, so that the granular filter media 52 is prevented from entering the primary filter core 20 to contaminate the clean fluid.

FIGS. 5A and 5B detail a flow pattern that is the reverse of the above described with the fluid entering the inside of primary core. FIGS. 5A and 5B also depict an alternate embodiment of the housing 36, wherein the outlet 46 is positioned on the side of the housing and instead of on the top. In this embodiment, the fluid enters through the opening 48 on the housing 36 and the bottom cap 42 into the primary filter core 20. The fluid then enters the voids 50, and passes through either the exterior filter 16 or an interior filter 18. In the later event, the fluid exits the interior filter 18 via the opening 32 a and 32 b of the secondary filter core 28. The fluid then exits the housing 36 via the outlet 46. The reverse flow pattern can be used to remove the impurities deposited on the filters after using the filtration segment 10 in the normal flow pattern for a period of time. The reversed flow pattern also helps to clean the filtration segment for reuse.

FIGS. 6 and 7 show an alternate embodiment of the current invention, wherein two filtration segments 10 are used with one being stacked on top of the other. FIG. 6 shows a normal flow pattern and FIG. 7 shows a reversed flow pattern. The flow patterns are described as above. The filtration segments 10 can be simply stacked upon each other. Alternatively, the filtration segments 10 can be secured by a stacking adaptor 70 or by any other means known in the art. Any number of filtration segments 10 can be used dependent upon the diameter, length and height of the housing 36.

FIGS. 8A, 8B and 8C show another alternate embodiment of the current invention, wherein only a portion of the fluid is filtered and the rest exits the filtration assembly unfiltered. This flow pattern is generally referred to as “cross-flow” configuration in the current invention. Specifically, FIG. 8A shows a “cross-flow” filtration assembly wherein only one filtration segment is used and FIG. 8B shows a “cross-flow” filtration assembly wherein two filtration segments 10 are stacked together. In both FIGS. 8A and 8B, fluid first enters the filtration segment 10 via the inlet 46. Thereafter, the fluid follows one of the following two paths.

-   -   A portion of the fluid enters openings as illustrated by 32 a         into the secondary filter cores 28 a and passes through the         interior filters 18, or flows along the inner walls of the         housing 36 to the peripheral area surrounding the exterior         filter 16 and then passes through the exterior filter 16. The         filtered fluid is collected at the primary filter core 20 and         exits the filtration segment 10 via the outlet 48.     -   The rest of the fluid flows along the inner walls of the housing         36 and exits the filtration segment 10 unfiltered via a         “cross-flow” outlet 47, which, as shown in the current         embodiment in FIG. 8A, is positioned at the lower right corner         of the filtration segment 10.

FIG. 8C is a schematic drawing showing the flow pattern of a “cross-flow” configuration according to one embodiment of the invention. First, fluid to be filtered enters the filtration assembly via the inlet 46. A pump 100 can optionally be used to facilitate the process. A portion of the fluid is filtered and exits the filtration assembly via the outlet 48 and is collected in a clean tank 110. The rest of the fluid is not filtered and exits the filtration assembly via the “cross-flow” outlet 47. The unfiltered fluid is collected in a dirty fluid tank 120 and re-enters the filtration assembly via the pump 100 (optional) and the inlet 46. Additional dirty fluids can be added into the dirty fluid tank 120 from sources such as container 130, etc.

One benefit of the “cross-flow” configuration is its flexibility in filtering different types of fluids. The flow velocity and/or the filtration pressure can be adjusted and different influx/efflux ratios can be achieved. In some embodiments, it is preferable to have an influx/efflux ratio of about 1:1. In some other embodiments, it is preferable to have an influx/efflux ratio of about 10:1. Generally speaking, when the dirty fluid contains a substantial amount of solid impurities, a higher influx/efflux ratio may be preferred.

FIG. 9 shows another embodiment of the “cross-flow” configuration. Here, the inlet 46 and the outlet 48 are positioned at a substantially same level, and such level is relatively distant from the filtration assembly. On the other hand, the cross-flow outlet 47 is positioned at a location that is relatively proximate to the filtration assembly. Therefore, the filtration assembly can be positioned at a location that is distant from the influx/efflux pipeline, and the inlet 46 and outlet 48 can be more easily streamlined with other equipments of the plant In the particular embodiment as shown in FIG. 9, a primary tube 140 in the core 20 and one or more secondary tubes 150 are used to ensure the proper segregation of clean fluid from dirty fluid. The primary tube 140 comprises an upper portion 140 a and a lower portion 140 b. The upper portion 140 a generally occupies the primary core 20 of the filtration segment 10 and is preferably fluid-permeable so that filtered fluids can enter into the tube and flow to the lower portion of the tube 140 b. On the other hand, the lower portion of the tube 140 b is preferably fluid-impermeable. It extends downwardly from the upper portion of the tube 140 a until it reaches the level of the inlet 46 and the outlet 48, and then turns and exits the filtration assembly via outlet 48.

The secondary tubes 150 are attached to the bottom openings 32 b of the secondary filters 18 and collect unfiltered fluid from openings 32 b. The secondary tubes 150 form a circular concentric chamber that is in fluid communication with openings 32 b below the bottom seal and surrounding the primary tube 140 and are in fluid communication with the filtration assembly via the “cross-flow” outlet 47. The secondary tubes and chamber formed by the tubes 150 is fluid-impermeable.

FIG. 10 shows yet another embodiment of the invention. In this embodiment, the top seal 80 contains no openings, and no rod or nut is used to assemble the filtration segment 10 to the housing 36. Fluid first enters from the inlet 46, flows along the top seal 12 to the peripheral area of the filtration segment 10. Thereafter, a portion of the fluid passes through the exterior filter 16 into the voids 50 (not shown) and eventually congregates at the primary core 20. The rest of the fluid enters the openings 32 b at the bottom of the interior filters 18, passes the interior filters 18, and again congregates at the primary core 20. The filtered fluid eventually exits the filtration assembly via the outlet 48.

This invention is also for a new method of filtering fluid. The fluid flows around a generally cylindrical exterior layer of filter media and part of the fluid passes through the media. At the same time the remaining fluid passes through cores of generally cylindrical filter media inside the cylindrical exterior media allowing the fluid to pass outside the cores of the interior filters to a collection space inside the exterior layer. The filtered fluid is collected in the core spaces formed by the exterior wall of the cylindrical exterior layer of filter media and the exterior walls of the interior filters.

The reverse filter flow may also be used. The fluid to be filtered flows through the interior to the exterior of a generally cylindrical fluid permeable outer filter media layer allowing part of the fluid to pass through the filters media. At the same time fluid flows through the interior to the exterior of more than one generally cylindrical filter medias surrounded by the outer filter media so the fluid passes to the cores of the interior filter medias. The filtered fluid that passes through the outer filter media and interior filter media cores is collected.

While the invention has been described with respect to a limited number of embodiments, depending, for example, upon the fluid to be filtered, the pressure drop across the filter, and the direction of filtration, a virtually endless number of filter segments and filter assemblies may be employed. Also, the specific features of one embodiment should not be attributed to other embodiments of the invention and no single embodiment is representative of all aspects of the inventions. Moreover, variations and modifications therefrom exist. The appended claims intend to cover all such variations and modifications as falling within the scope of the invention. 

1. A method for filtering a fluid comprising the steps of: (1) flowing a fluid around a generally cylindrical exterior fluid permeable filter media allowing part of the fluid to pass through the filter media; (2) at the same time as step (1), flowing the remaining fluid through cores of more than one generally cylindrical filter media inside the exterior media and allowing the fluid to pass through the filter media; and (3) collecting said fluid that has passed through the exterior filter media and the media inside the exterior media.
 2. A method for filtering a fluid comprising the steps of (1) flowing the fluid through the interior to the exterior of a generally cylindrical fluid permeable outer filter media layer allowing part of the fluid to pass through the filter media; (2) at the same time as step (1) flowing the remaining media through the interior to the exterior of more than one generally cylindrical filter medias surrounded by the outer filter media so the fluid passes to the cores of the interior filter medias; and (3) collecting the fluid that has passed through the outer filter media and the interior filter media cores. 